Generally, reflecting solar troughs are made of shiny metal sheets which are backed by supporting ribs. Primarily because of manufacturing limitations at the mill there are necessary restrictions on the areas of the sheets. Consequently, a multiplicity of reflectors are often required for a given solar energy project. As a rule, the sheets with rigid supporting ribs are assembled at a plant site because of the difficulty and expense in attempting to assemble the sheets and ribs in the field. As a result, the mirrors are heavy and bulky and difficult to ship. This adds cost to the finished product.
U.S. Pat. No. 4,293,192, issued Oct. 6, 1981, to Allen I. Bronstein, sets forth a solar reflector which is collapsible and portable and which will maintain its true configuration without the requirement of supporting ribs. The invention of U.S. Pat. No. 4,293,192 includes the use of a slideway on which two form members are supported, the form members having identical surfaces around a portion of their peripheries, which identical surfaces conform precisely to the desired configuration of the reflecting surface. A sheet of highly reflecting material is wrapped tightly around the surfaces and secured in place, and at least one of the forms is mounted on a slide which is moved away from the other form until the flexible sheet is in tension. Thereby, the flexible sheet conforms precisely to the curve of the form surfaces over its full length. The slideway is pivoted on support legs so that it may be tilted at a selected angle, depending on the angle of the sun. Strips of tape may be adhered to the outer or convex surface of the material to dampen it against wind vibration.
While the invention of U.S. Pat. No. 4,293,192 provides significant advantages over the prior art rib-supported solar reflectors, the apparatus taught therein is of relatively heavy construction, is not as easily tiltable as might be desired, is not readily expandable to form a bank of solar reflectors which are adjustable together, and is not as readily assemblable as might be desired.